Broadband wireless communication systems, currently under development, support very high rate wireless Internet based on Institute of Electrical and Electronics Engineers (IEEE) 802.16.
The IEEE 802.16 standard suggests diverse versions by reflecting various technical suggestions and standards. For example, the IEEE Standard (Std) 802.16-2004 concerns the air interface and describes the interface between a terminal and a base station of the physical layer and the Media Access Control (MAC) layer. The IEEE Std 802.16e-2005 describes the interfaces of the physical layer and the MAC layer in addition to the IEEE Std 802.16-2004 so as to support the mobility. The IEEE 802.16f-2005 defines the interface among network resources.
The IEEE standard documents are amended to enhance the performance, to correct operation scenario errors, or to clarify the interface; and then the draft versions are distributed. The draft versions are stabilized, through much discussion, and then formal versions are released. For example, the IEEE Std 802.16e-2005 includes the draft version documents of Corrigenda2. Currently, the IEEE 802.16 maintenance group is distributing the revision document, which is the unified document including the drafts of IEEE Std 802.16-2004, IEEE Std 802.16e-2005, IEEE Std 802.16f-2005 and Cor1, IEEE Std 802.16g-2007, and Corrigenda2.
As the IEEE 802.16 standard documents are amended and their new versions are released, WiMAX defines several criteria in the commercialization. The mobile WiMAX Rel 1.0, in the process of the commercialization, is based on the IEEE Std 802.16-2004, the IEEE Std 802.16e-2005 and Cor1, and the Corrigenda2 Draft-3. It is intended that the mobile WiMAX Rel 1.5 will be based on the revision document in progress.
The version may differ depending on a provider or an authentication profile. The system upgrade may cause the coexistence of multiple terminals having the different versions. In this respect, a network access scenario based on the different standard versions requires consideration. The current IEEE 802.16 standard defines that the standard versions supported by the base station and the terminal should be represented using MAC version Type-Length-Value (TLV). The base station should include the MAC version TLV in a broadcast message such as Downlink Channel Descriptor (DCD) and the terminal should include the MAC version TLV in a Ranging (RNG)-Request (REQ) message. For example, to support the IEEE Std 802.16-2004, the IEEE Std 802.16e-2005 and Cor1, and the Corrigenda2, the MAC version value is set to ‘6’. To support the IEEE Std 802.16-2004 and the IEEE Std 805.16e-2005 and Cor1 and not to support the Corrigenda2, the MAC version value is set to ‘5’. To support the IEEE Std 802.16-2008 of the Revision, the MAC version value is set to ‘8’.
When the MAC versions supported by the base station and the terminal are different from each other, the communication may be disapproved or the communication may be carried out with the low MAC version. Practically, in the system upgrade, the terminal supporting the old version may coexist with the terminal supporting the new version. It is necessary to concurrently support both of the terminal of the old version and the terminal of the new version until all of the terminals and the systems in the network are upgraded with the new version. Alternatively, it is necessary to support the multiple version at the same time by taking into account all of the system of the old version and the system of the new version. However, the current MAC version TLV value can represent only one of the versions supported by the terminal and the base station and cannot indicate which versions are supportable.
More particularly, since the conventional technique indicates only one version value in the DCD message and the RNG-REQ message, the possible scenarios for the base station and the terminal capable of supporting the multiple versions are quite restricted.
For instance, when the base station transmits the MAC version TLV value ‘6’ of the DCD message and the terminal supporting the MAC versions ‘6’ and ‘8’ accesses to the corresponding network in the system capable of supporting the MAC version ‘6’, the MAC version TLV value of the RNG-REQ message can be set to ‘8’. The system cannot know whether the terminal can support the MAC version ‘6’ or not. Naturally, the communication of the terminal which accesses with the MAC version TLV not supported in the system is highly likely to be disapproved.
For example, it is assumed that the base station can support the MAC versions ‘5’ and ‘8’ and the terminal can support the MAC versions ‘5’ and ‘6’. The base station sets the MAC version of the DCD message to ‘8’ and the terminal sets the MAC version of the RNG-REQ message to ‘6’. In reality, while the base station and the terminal can communicate with each other with the MAC version ‘5’, the communication is rejected because the version is not identified.
Therefore, when the broadband wireless communication system supports the plurality of the MAC versions, a method and an apparatus for avoiding the communication rejection caused by the version mismatch are demanded.